Satellite based systems are increasingly used for the transmission of television programming. Typically, a geostationary satellite receives a terrestrial signal and downlinks the signal to ground based antennas located in the satellite's coverage area. The ground based antennas typically include a parabolic antenna and a low noise block which amplifies, filters, and shifts the frequencies of the received signal to an intermediate frequency for coupling with a receiver.
In order to increase the bandwidth of the signal from the satellite, the signal is sent in two polarities. For example, the two polarities may be out of phase by 90° which doubles the usable bandwidth of the satellite signal. The low noise block of the ground based antenna must then separate the separately polarized signals and send them to the receiver.
At times, it is difficult to receive optimum performance from satellite signals. For example, interference from one broadcast channel can degrade the reception of other channels. For a user, this results in less picture definition and a higher signal to noise ratio.